| 摘要 |
PURPOSE:To eliminate the need for circuit constitutions by voltage specifications, driving light emitting elements in automatic correspondence to supply voltages and yet maintain constant brightness without power consumption by selectively controlling by series or parallel non-contact system at least two light emitting elements according to the levels of the supply voltages. CONSTITUTION:When a supply voltage E is lower than the zener voltage of detection part SVC, TR5 goes OFF and TR6 thru TR8 go ON, letting TR3 go ON. At this time, TR9 goes ON and therefore TR1, TR4 go ON and TR2 goes ON. Hence, D1 and D2 as well as D3 and D4 are parallel connected. If the voltage E is higher than the zener voltage of the detection part, TR5 goes ON and TR6 thru TR8go OFF and therefore TR3 goes ON and TR9 goes ON to cause TR1 and TR2 to go OFF, then D1 and D2 as well as D3 and D4 are series-connected. Since a Schmitt circuit is formed by TR5, TR6, series-parallel changeover action may be effected sensitively. |
